The present invention relates to a reinforced structural member for use in applications where load carrying capability is required, for example structural, semi-structural and cladding applications to carry floor loading, walkway loading, wheeled loading, pressure loading in buildings, bridges etc.
Traditionally, solid members have been used in the above applications. Recently sectioned members have been proposed but these are mainly box-section members such as those described in WO 91/06421.
The present invention provides an elongate structural member comprising an outer shell having a quadrilateral lateral cross section with opposite faces substantially parallel and at least one reinforcing member within the outer shell.
The reinforcing member may be arcuate in a plane perpendicular to the axis of said structural member and extend between positions near opposite edges of one major face of the outer shell. The mid section of the reinforcing member then approaches near the opposite face.
Alternatively, the reinforcing member may be straight and extend between the major faces of the outer shell. Where the outer shell is not rectangular in cross-section, i.e. the minor faces are not perpendicular to the major faces, it is particularly preferred that some or all of the reinforcing members are oppositely inclined to the minor faces. A particularly strong structure which is simple to manufacture can be formed by arranging a single internal reinforcing member which is oppositely inclined to the minor faces of the outer shell and extends generally along the shorter diameter of the shape formed by the outer shell in cross-section.
The present invention provides a member which has improved strength characteristics by efficiently transmitting loads to the bottom corners or intermediate points across the section, while providing stiffness in the longitudinal direction, preventing local buckling of the wide upper flange and resistance to in-plane loading.
It is envisaged that the space between the arcuate member and the load bearing surface opposing the arcuate surface may be filled with a foam material and/or may have rib members extending between them.
Both the outer shell and the arcuate member may be constructed by either molding or pultruding them from fiber reinforced composite materials. This provides the member with the strength required whilst retaining a lightweight construction.
When load is applied to the load bearing surface, it is passed through the arch to the base of the structural member where it is transmitted to the supports at suitable points along the length of the member. In order to prevent the ends of the arch from splaying outwards they are restrained in one of two ways. Either, a planar sheet of a similar material to the rest of the outer shell is used to restrain the ends of the arch and also forms the base of the structural member or tension members such as wires or strips are provided spaced along the length of the structural member connecting the opposite sides of the arch to hold them in position.
It is also envisaged that to provide improved performance especially when high in-plane forces are encountered, reverse arching may be used. In such instances the structural member would contain two intersecting arcuate members, one hogging and one sagging. This also allows the member to be used either way up, avoiding the need to check which way up the arcuate member is within the outer member when positioning the member.
If the structural members are to be used in combination, connecting portions may be provided to allow attachment of the units to each other to form floors, decks, roofs, walls, beams and columns of buildings, bridges and other forms of structure.
If the structural members are to be suspended in use then hanger portions may be provided to allow attachment to the hanging means.